Abstract : The aim of this work was to understand the reactions that appear during glycolytic depolymerization of an epoxide-amine hardened thermoset. A model compound (product of condensation of phenylglycidyl ether to N,N'-dimethylethylenediamine) of the epoxy thermoset was synthesized to simplify the study. By reaction with 1,4-butanediol, a cleavage of the rho-O-C linkage occurs, leading to formation of phenol.
A stagnation of the yield in phenol at about 20% was observed for the uncatalysed reaction. Different catalysts were checked (sodium methylate, titanium(IV) n-butoxide, lithium perchlorate and p-toluenesulfonic acid). The most efficient of them are p-toluenesulfonic acid (3 w/w%) and sodium methylate (30 w/w%). The disappearance of the initial model compound was also observed, even for a low yield in phenol.
The different reaction products were separated and analysed by NMR spectroscopy. The results are in accordance with a reaction scheme based on two mechanisms of rho-O-C linkage cleavage.